Combined detergent-corrosion inhibitors



United States Patent 3,287,271 COMBINED DETERGENT-CORROSION INIrHBITORS Frank A. Stuart, Orinda, and Warren Lowe, Berkeley,

Calif., assignors to Chevron Research Company, a corporation of Delaware No Drawing. Filed Jan. 21, 1965, Ser. No. 427,176

9 Claims. (Cl. 25249.9)

This application is a continuation-in-part of Frank A. Stuart and Warren Lowe, US. application Serial No. 220,573, filed August 30, 1962, now abandoned.

This invention concerns novel lubricating oil compositions containing a combined detergent-corrosion inhibitor. More particularly, this invention concerns novel lubricat ing oil compositions containing amine carboxylic acid products as detergent-corrosion inhibitors.

Present-day internal combustion engines operate at high speeds and high compression ratios. When used in the so-called city stop-and-go driving, which includes the greater part of the driving conditions for a large percentage of todays automobiles, the internal combustion engines-do not reach the most efiicient operating temperatures. Under city driving conditions, large amounts of partial oxidation products are formed, and reach the crankcase of the engine by blowing past the piston rings. Most of these partial oxidation products are acidic in nature, tending to form deposits which corrosively attack the various operating parts of the engine, such as the pistons, piston ring bearings, etc. For the purpose of preventingsuch deposition and corrosivity by these prodnets on the various engine parts, it is necessary to incorporate detergents and corrosion inhibitors in the lubricating oil composition, thus keeping the corrosion products dispersed in a condition unfavorable for metals.

Al-so, when water is present, iron will corrode or rust. Frequently, corrosion inhibitors will protect lead or copper parts from corrosion, but are ineffective against rusting. Alternatively, rusting may be inhibited while other types of corrosion persist.

Numerous detergents added to crankcase oils .to reduce the formation of sludges and varnish, as well as corrosive attack on metal parts, are metal organic compounds, particularly those compounds in which the metal is linked to an organic group through an oxygen atom. Although these metal-containing organic compounds have corro sion inhibition capability as well as detergency, they form undesirable ash deposits in the engine. These ash deposit-s lower engine performance by fouling spark plugs in valves, and contribute to preignition.

Pursuant to this invention, novel compositions which provide both corrosion inhibition and detergency are provided which are obtained by combining a polyamine with a high molecular weight succinic anhydride and then contacting the resulting product with a dicarboxylic acid, having the carboxyl groups separated by at least three annular carbon atoms (3 to 4 annular carbon atoms). The product is obtained by combining at an elevated temperature an alkenyl succinic anhydride, wherein the alkenyl group has from about 30 to 200 carbon atoms, with a polyamine free of unsaturation (both aliphatic and aromatic) and having from 2 to carbon atoms and from 2 to 10 nitrogen atoms; then combining at elevated temperatures the above product with an aromatic dicarboxylic acid, characterized by having carboxyl groups bonded to annular carbons separated by at least one annular carbon .atom (the carboxylic groups are, therefore, separated by at least three annular carbon atoms) and having a total of from 8 to 16 carbon atoms.

3,287,271 Patented Nov. 22, 1966 The alkenyl succinic anhydride reactant has the following formula:

wherein R is a hydrocarbon radical having from 3010 200 carbon atoms, preferably from about 50 to about 200 carbon atoms.

The R radical of the above formula, that is, the alkenyl radical, is readily obtained by polymerizing olefins of from 2 to 5 carbons, such as propylene, ethylene, isobutylene, pentene, etc., and mixtures thereof. Methods of polymerization are well known in the art, e.g., US. Patents Nos. 3,024,237, 3,024,195 and 3,018,291.

The amine with which the alkenyl succinic anhydride is reacted .is a polyamine having from 1 to 2 primary amino groups, is of from 2 to 20 carbon atoms, has from 1 to 11 nitrogen atoms, preferably 1 to 6 nitrogen atoms (as its only heteroatoms) and is free of unsaturation. The nitrogen atoms will be joined by :alkylene groups of from 2 to 6 carbon atoms, more usually of from 2 to 3 carbon atoms and, except the primary amino groups, will be substituted with hydrogen or lower alkyl, i.e., l to 6 carbon atoms, more usually of from 1 to 3 carbon atoms.

The organic polyamines of this invention will, for the most part, come within the scope of the following formula:

wherein T is alkylene of from 2 to 6 carbon atoms, more usually of from 2 to 3 carbon atoms, x-l-y is an integer of from 1 to 10, y is a cardinal number of from 0 to 2, and x is a cardinal number of from 0 to 10, Y is either hydrogen, --TNU U or lower alkyl, U and U being either hydrogen or lower alkyl. Usually, the polyamines of the above formula will have from 2 to 20 carbon atoms, more usually from 4 to 16 carbon atoms.

A preferred subgenus has the following formula:

wherein T is :alkylene of from 2 to 3 carbon atoms and x is an integer of from 1 to 10, more usually from 1 to 5. Illustrative of various alkylene amines and polyalkylene amines of the following formula are diethylene triamine, triethylene tetramine, dipropylene triamine, tetraethylene pentamine, pentaethylene hexamine, no'naethylene deoamine, etc.

Another preferred sub-genus is the alkyl-substituted alkylene diamines of the following formula wherein T is alkylene of from 2 to 6 carbon atoms, preferably 2 to 3 carbon atoms, and U and U are lower alkyl, i.e., alkyl of from 1 to 6 carbon atoms. Exemplifying compounds included in the above formula are dimethylaminopropylamine, diet-hylaminopropylamine, diethylaminobutylamine, dipropylaminobutylamine, diethyl aminoethylamine, etc. The total number of carbon atoms will generally be in the range of about 4 to 12, more usually 5 to 10.

A further subgenus has the following formula:

wherein T is alkylene of from 2 to 6 carbon atoms and U is hydrogen or an alkyl radical of from 1 to 6 carbon atoms. Illustrative of compounds exemplifying the above formula are N-(2-aminoethyl)piperazine, N-rnethyl-N'- (2 aminoet-hyDpiperaZine, N (3 aminopropylene) piperazine, etc.

For purposes of brevity, the products obtained by reacting alkenyl succinic anhydrides and the polyamines described above will be termed N-substituted alkenyl succinimides. The N-substituted alkenyl succinimides are prepared by reacting at elevated temperatures an alkenyl succinic anhydride with the desired polyamine, generally in the presence of an inert medium. The polyamine-anhydride mole ratio will generally be in the range of from 0.5:1 to 1:1, more usually in the range of 0.821.

The temperature for the reaction will generally be from about 200 to 500 F., more usually from 225 to 400 F.

The concentration of the reactants in the inert medium may range from 1 to 90 weight percent, but will more usually be from about 25 to 75 weight percent of the total reaction mixture.

The time for the reaction will generally be from about one-half hour to 24 hours or more, more usually in the range of about 1 to 12 hours.

During the reaction, it may be desirable to distill off the water that is formed from the reaction between the amine and the succinic anhydride; however, this is not essential to the reaction. The removal of the water may be carried out by any means known in the art. Subatmospheric pressure may be used with advantage.

The inert medium may be any dispersant or solvent that permits sufiicient contact between the reactants to provide a reasonable rate of reaction. The solvent should be a liquid under the reaction conditions. Conveniently, an oil of lubricating viscosity, which is also a solvent, can be used, e.g., petroleum oils, such as paraffinic, aromatic and naphthenic oils.

As already indicated, the carboxylic acids which find use in this invention are dicarboxylic acids of from 8 to 16 carbon atoms having from to 2 alkyl substituents of from 1 to 8 carbon atoms and the carboxyl groups are separated by at least three annular carbon atoms. The compounds may be described by the following formula:

I COzII where the brace indicates the two positions to which the carboxyl may be bonded, U is lower alkyl, i.e., alkyl of from 1 to 6 carbon atoms and x is a cardinal number of from 0 to 3, preferably from 0 to 1. Illustrative of compounds included in the above formula are isophthalic acid, terephthalic acid, 4-methyl isophthalic acid, 4-isopropyl isophthalic acid, 2-(tert.-butyl)terephthalic acid, 5-(tert.-butyl)-isophthalic acid, 2,5-(dimethyl)tereph thalic acid, 2,5-di(tert.-butyl)terephthalic acid, 4,6-di- (methyl)isophthalic acid, etc.

Generally, about 1 mole of the dicarboxylic acid will be combined with 1 mole of the N-substituted alkenyl succinimide. With N-substituted alkenyl succinimides which have more than one basic titratable amino nitrogen atom, more than 1 mole of carboxylic acid per mole of succinimide may be used. Representing the number of basic titratable amine nitrogen atoms of the succinimide with x, the number of carboxylic acids which may be used will range from 1 to x, more usually from 1 to x1, but not less than about 1.

On a weight basis, the succinimide-dicarboxylic acid weight ratio in the finished lubricating oil composition will be less than 200:1, preferably less than 100:1, and more preferably in the range 50-1: 1.

The combining of the succinimide with the carboxylic acid is achieved by heating the carboxylic acid and succinimide in the presence of an inert medium, generally an oil of lubricating viscosity, to a temperaturein the range of about 200 to about 300 F., more usually from about 270 to 290 F. When an oil of lubricating viscosity is used as the medium, the composition may be prepared as a concentrate which may be diluted with other oils to form the final lubricating oil composition.

The compounds of this invention may be used with various base oils which find use as lubricating oils, such as petroleum oils, i.e., naphthenic base, paraffin base and mixed base lubricating olls; synthetic oils, e.g., alkylene polymers (such as polymers of butylene, l-decene, etc.), alkylene oxide type polymers (e.g., propylene oxide polymers); dicarboxylic acid esters; liquid esters of acids of phosphorus; alkyl benzenes; alkyl biphenyl ethers; alkyl or aryl silicon compounds, etc.

The above base oils may be used individually or in combination whenever miscible or made so by the use of mutual solvents.

The compounds of this invention can be used in oils of lubricating viscosity in amounts of from about 0.1 to weight percent. When the oil is used in an engine, usually the amount will be about 0.1 to 10 weight percent, more usually 0.25 to 5 weight percent. However, the oil compositions may be prepared as concentrates and diluted prior to use. As concentrates, the amount of the active compound may range from about 10 to 80 weight percent.

In the finished oil the oil to be used in the enginethe dicarboxylic acid will be present in amounts of 0.001 to 0.75 weight percent, preferably 0.005 to 0.25 weight percent.

The detergent-corrosion inhibitors of this invention are preferably used in conjunction with a metal salt of a phosphorodithioate, particularly zinc 0,0-di(hydrocarbyl)-phosphorodithioate, wherein the hydrocarbyl group is of from 4 to 36 carbon atoms. (By hydrocarbyl is intended a monovalent organic radical composed solely of carbon and hydrogen which may be aliphatic, aromatic, alicyclic, or combinations thereof, e.g., aralkyl.) Usually about 6 to 50 mM./ kg. of the metal thiophosphate is used in the engine oil.

A preferred composition is to include with the detergentcorrosion inhibitors of this invention tricresyl phosphate. The addition of the tricresyl phosphate imparts the extreme pressure characteristics necessary for oils operating under heavy loads to avoid valve lifter scufiing and camshaft scuffing. The amount of the tricresyl phosphate will generally be in the range of about 0.1 to 3 weight percent.

The following examples are offered by way of illustration and not by way of limitation.

Example A A mixture of 1000 g. (1 mole) of polyisobutylene (approximate molecular weight=1000) and 98 g. (1 mole) of maleic anhydride were heated at 410 F. in a nitrogen atmosphere with agitation for a period of 24 hours. The reaction mixture was cooled to 150 F. and 700 cc. of hexane added; after which, the mixture was filtered. The hexane was removed in vacuo and the residue heated at 350 F. at 10 mm. Hg for 1 hour to remove traces of maleic anhydride. The polybutenyl succinic anhydride thus prepared had a saponification number of 79 (meq. KOH/ 1 g. of sample).

A portion of the above product (702 g., 0.45 mole) and 84 g. (0.45 mole) of tetraethylene pentamine was blended with agitation at F. in a nitrogen atmosphere. The temperature was then increased to 400 F. for a period of 1 hour, after which time the absolute pressure was reduced to about 200 mm. Hg during a period of 30 minutes to facilitate the removal of water. The reaction mixture was allowed to cool at room temperature while maintaining the reduced pressure.

Example B Into a reaction flask was introduced 18 g. (0.4 mole) of N-(B-aminoethyl)piperazine and 200 g. (0.127 mole) of the polyisobutenyl succinic anhydride prepared as described in Example A and mixed with agitation in a nitrogen atmosphere. The mixture was heated for 1 hour at 500 F., the pressure was then reduced to about 200 mm. Hg and water and unreacted piperazine removed. The mixture was then allowed to cool. The infrared spectrum Was consistent with the succinimide structure. Analysis: percent N=2.59.

Example I A mixture of 36 -g. of terephathalic acid, 540 g. of a product prepared as in Example A (the polyisobutenyl radical contained 66 carbon atoms) and 756 g. of a California SAE 30 base oil was agitated at 295300 F. for 1.5 hours under a blanket of nitrogen.

An oil concentrate of the above product was formed by blending with agitation 1250 g. of the above product and 1250 g. of a California paraffinic base oil having a viscosity of 150 SSU at 100 F. by heating the mixture at 280 F. for minutes.

Example 11 A succinimide prepared as described in Example A (1970 g.) was charged to a reaction vessel and blanketed with nitrogen. The succinimide was then heated to 265 F. at which temperature 56.2 g. of terephthalic acid was then added. The temperature was then raised to 300 F. during a period of 1 hour and maintained for an additional 4 hours, then cooled to 250 F. and filtered.

Example Ill The procedure of Example II was repeated using tert.- butyl isophthalic acid in place of terephthalic acid.

Example IV The procedure of Example II was repeated using isophthalic acid in place of terephthalic acid.

The compositions of this invention were tested under numerous conditions to demonstrate their effectiveness as a combined detergent-corrosion inhibitor.

The following data were obtained in a L-38 test, using a l-cylinder CLR engine. The test was for 40 hours, with an engine speed of 3150 rpm. The results are reported as the bearing weight loss in milligrams. The base oil was a Mid-Continent SAE 30 base oil. The succinimides prepared as previously described were combined with the indicated acid as described in exemplary Examples 1-14. The following table indicates the results.

5.5 wt. percent of mixed 012-1: alkyl rnethaerylate-vinyl pyrrolidone copolymer of mol. wt. -475,000 and 0.1 wt. percent of cetyl methacrylate polymer of mol. wt. -220,000 was also added.

1 The succinimide is one prepared as described in Example A.

2 TPA-terephthalic acid. B-IPA-5-tert-.butyl isophthalio acid.

9 ZnO-butyl Opentyl phosphorodithioate.

4 Zn0,0-alkylphenyl phosphorodithioate (alkyl of from 12-15).

Repeating the L-38 test, using 2.0 weight percent of a succinimide prepared as described in Example A in a Mid-Continent SAE 30 oil, without the presence of phospercent.

6 phorodithioate, for a period of 40 hours, the following results were obtained.

TABLE II Dicarboxylic 1 Acid Wt. Percent Bearing Weight Loss, mg.

2 1, 267 IPA 0.05 253 1 IPA-isophthalic acid. TPAterephthalic acid. 2 The run was carried out for only 20 hours.

Copper and lead strips were immersed in oil formula tions using California paraflin base oil having a viscosity of about 500 SSU at F. at a temperature of 340 F. for 20 hours and the weight loss determined at the end of this time. The following table indicates the results. The succinimide and carboxylic acid were combined as described in exemplary Examples 14.

TABLE III Strip Weight Succinimide, Dicarboxylic Acid, Loss (mg) wt. percent wt. percent Copper Lead 1 A-1 succinimide prepared as described in Ex. A. Total N, 1.8 wt. A-2 succinimide prepared as described in Ex. A. Total N, 2.2 wt. percent. B-l succinimide prepared as in Ex. B.

TPA-terephthalic acid. IPA-isophthalic acid. BIPA5-tert.- butyl isophthalic acid.

The following data were obtained in an L-4 Chevrolet Engine Test after 36 hours. The base oil was a California parafiin base oil having a viscosity of about 500 SSU at 100 F. The succinimide and carboxylic acid were combined as described in exemplary Examples 14. The results were reported as bearing weight loss in milligrams.

TABLE IV Snccinimide, wt.

Dicarboxylic Acid, Percent TABLE V Oil 1 Containing Reference Oil GM Additive 6063 Lifter (avg) 8.5 6. 6 Push Rods". 5. 7 6.8 Engine (avg.)-. 7.9 6. 7

1 The oil contained 10 rnMJkg. of M 0,0-dialkyl phosphorodithioate (alkyl 0! from 4 to 6 carbon atoms), 2 rnM./kg. of M 0,0-dialkylphenyl phosphorodithioate (alkyl of from 12 to 15 carbon atoms). 2 wt. percent of a succinimide prepared as described in Example A and 0.15 wt. percent of tert.-butyl isophthalie acid.

The compounds of this invention were also tested in the Steel Ball Rust Test. The test comprises immersing clean steel balls-whioh are pre-soaked in test oils for one minute at 115-l20 F. and then allowed to drain for one minutein an emulsified test oil (The emulsified test oil is prepared by rapidly stirring 300 ml. of the test oil with a 9 ml. solution of equal parts by volume of cone. HCl, conc. H 50 and glacial acetic acid.) for 20 hours with stirring at 140 F. The steel ball is then removed from the bath, rinsed with acetone and rated on a to scale, 10 being no rust, 0 being heavy rust. The oil used was a Mid-Continent SAE oil, containing 10 mM./leg. of Zn 0,0-dialkyl dithiophosphate (alkyl of of from 46 carbon atoms) and 2 mM./k-g. of Zn 0,0-dialkylphenyl phosphorodithioate (alkyl of from 12l5 carbon atoms).

l ASuceinimidc prepared as in Example A. B-Suecinimido prepared as in Example B.

2 AIPAtert.-a1nyl isophthalic acid.

BIPAtert.butyl isophthalic acid.

The presence of small amounts of the dicarboxylic acids of this invention greatly inhibit rusting. The preferred dicarboxylic acids are those having alkyl substituents of from 4 to 8 carbon atoms, e.g., tert.-butyl terephthalic acid, tert.-hexyl isophthalic acid, octyl isophthalic acid, etc.

The following data demonstrate the effectiveness of the combination of tricresyl phosphate wit-h the compositions of this invention as extreme pressure additives. The following table presents data obtained in a Falex Extreme Pressure Load Test. The figures are by loads in pounds at which there was lubrication failure. The base oil used was California pa rafiin base oil having a viscosity of about 500 SSU at 100 F.

TABLE VII 1 One weight percent of commercial oxidation inhibitor was included in the composition.

To demonstrate the detergency of the compositions of this invention, 2 weight percent of the succinimide prepared as described in Example A was used with 0.05 Weight percent of terephthalic acid in a solvent refined base oil SAE and tested under L-l, Supp. 1 conditions (MILL2104B, Supp. 1 specifications). The test was carried out for 120 hours. 100 indicates a completely filled groove, while 0 indicates a completely clean groove. 800 indicates a completely coated land, while 0 indicates a completely clean land. For the base oil without additive, the groove numbers were 20, 20, 10, 7 and the land numbers were 755, 800, 800. For the same oil with the additive, the groove numbers were 14, 5, 2, 1 and the iand numbers were 240, 60.

It is evident from the prior data that by combining the succinimide detergents havin-g basic amines with dicarboxylic acids, as defined in this invention, at elevated temperatures, compositions :are obtained which not only provide good detergency, but excellent corrosion inhibition, including rust inhibition. Under a variety of conditions, as demonstrated by generally accepted testing procedures, the compositions of this invention have provided excellent protect-ion for the engines. Furthermore, when combined with tricresyl phosphate, good extreme pressure characteristics are demonstrated.

As will be evident to those skilled in the art, various modifications on this process can be made or followed, in the light of the foregoing disclosure and discussion,

without departing from the spirit or scope of the disclo-' sure or from the scope of the following claims.

We claim:

1. A lubricating oil composition comprising an oil of lubricating viscosity, and a product obtained by (1) reacting at a temperature in the range of from about 200 F. to 500 F:

(a) an alkenyl succinic anhydride having from 30 to 200 carbon atoms in the alkenyl radical, with (b) an alkylene polyamine having from 1 to 2 primary amino groups, from 2 to 20 carbon atoms and from 1 to 11 nitrogen atoms; wherein the mole ratio of the polyamine to the anhydride is from about 0.5:1 to about 1:1; followed by (2) reacting at a temperature in the range of about 200 to 300 F.,

(a) the product of (1) with (b) an aromatic dicarboxylic acid of from 8 to 14 carbon atoms having from 0 to 2 alkyl substitutuents and wherein the carboxyl groups are bonded to annular carbon atoms separated by at least one annular carbon atom;

such that the weight ratio of the product of (1) to the dicarboxylic acid of (2) is less than 200:1, the product of reaction (1) and (2) being present in said oil composition in amount of 0.001 to 0.75 weight percent based on dicarboxylic acid content.

2. A composition according to claim 1 wherein said dicarboxylic acid is terephthalic acid.

3. A composition according to claim 1 wherein said dicarboxylic acid is isophthalic acid.

4. A composition according to claim 1 wherein said dicarboxylic acid is tert.-butyl isophthalic acid.

5. A composition according to claim 1 wherein said alkylene polyamine is a polyamine of the formula wherein T is alkylene of from 2 to 3 carbon atoms and x is an integer of from 1 to 10.

6. A composition according to claim 1 wherein said alkylene polyamine has the formula wherein T is alkylene of from 2 to 6 carbon atoms, and U and U4 are lower alkyl.

7. A composition according to claim 1 wherein said dicarboxylic acid is terephthalic acid and said alkylene polyamine is a polyamine of the formula wherein T is an alkylene of from 2 to 3 carbon atoms and x is an integer of from 1 to 10.

8. A composition according to claim 1 wherein said dicarboxylic acid is terephthalic acid and said alkylene polyamine has the formula wherein T is alkylene of from 2 to 6 carbon atoms, and U and U are lower alkyl.

9 10 9. A composition according to claim 1 having from FOREIGN PATENTS 0.1 to 3 weight percent tricresyl phosphate. 208,447 6/1957 Australia References Cited by the Examiner 1367939 6/1964 France UNITED STATES PATENTS 5 DANIEL E. WYMAN, Primary Examiner.

3,216,936 11/1965 Le Suer 252-S1.5 X P. P. GARVIN, Assistant Examiner. 

1. A LUBRICATING OIL COMPOSITION COMPRISING AN OIL LIBRICATING VISCOSITY AND A PRODUCT OBTAINED BY (1) REACTING AT A TEMPERATURE IN THE RANGE OF FROM ABOUT 200* F. TO 500*F: (A) AN ALKENYL SUCCINIC ANHYDRIDE HAVING FROM 30 TO 200 CARBON ATOMS IN THE ALKENYL RADICAL, WITH (B) AN ALKYLENE POLYAMINE HAVING FROM 1 TO 2 PRIMARY AMINO GROUPS, FROM 2 TO 20 CARBON ATOMS AND FROM 1 TO 11 NITROGEN ATOMS; WHEREIN THE MOLE RATIO OF THE POLYAMINE TO THE ANHYDRIDE IS FROM ABOUT 0.5:1 TO ABOUT 1:1; FOLLOWED BY (2) REACTING AT A TEMPERATURE IN THE RANGE PF ABOUT 200* TO 300*F., (A) THE PRODUCT OF (1) WITH (B) AN AROMATIC DICARBOXYLIC ACID OF FROM 8 TO 14 CARBON ATOMS HAVING FROM 0 TO 2 ALKYL SUBSTITUENTS AND WHEREIN THE CARBOXYL GROUPS ARE BOND TO ANNULAR CARBON ATOMS SEPARATED BY AT LEAST ONE ANNULAR CARBON ATOM; SUCH THAT THE WEIGHT RATIO OF THE PRODUCT OF (1) TO THE DICARBOXYLIC ACID OF (2) IS LESS THAN 200:1, THE PRODUCT OF REACTION (1) AND (2) BEING PRESENT IN SAID OIL COMPOSITION IN AMOUNT OF 0.001 TO 0.75 WEIGHT PERCENT BASED ON DICARBOXYLIC ACID CONTENT.
 9. A COMPOSITION ACCORDING TO CLAIM 1 HAVING FROM 0.1 TO 3 WEIGHT PERCENT TRICRESYL PHOSPHATE. 